The invention relates to a method of filling containers, especially bags, with bulk material by a feeding funnel and a filler pipe. The filler pipe adjoins the lower end of the feeding funnel. The filler pipe includes an axially displaceable and rotatable conveying unit arranged co-axially in the filler pipe. Also, an axially displaceable and rotatable closing element is positioned at the lower end of the filler pipe. The closing element is firmly connected to the lower end of the conveying unit. Furthermore, the invention relates to a device for filling containers, especially bags, with bulk material. The device includes a feeding funnel and a filler pipe. The filler pipe adjoins the lower end of the feeding funnel. The filler pipe includes an axially displaceable and rotatable conveying unit arranged co-axially in the filler pipe. Also, an axially displaceable and rotatable closing element is positioned at the lower end of the filler pipe. The closing element is firmly connected to the lower end of the conveying unit.
A method and device are known from DE 199 62 475 A1. Here a worm-or-spiral-shaped conveying unit, at its lower end, is firmly connected to a closing cone. Accordingly, a joint rotary drive and a joint lifting drive can be used for the conveying unit and the closing element. In a preferred embodiment, it is possible to continuously adjust the lifting height of the closing element and to rotatingly drive the closing element when the closing element is open. This achieves particularly advantageous dispensing results while avoiding the risk of the formation of bridges in the exit gap between the filler pipe and the closing element. If the bulk material is sticky it constitutes a problem. When conveying sticky material, it is possible, in spite of the forced conveyance taking place from the filler pipe to the exit gap, for the sticky material to continue to form bridges in, and adhere to the wall of the feeding funnel. The bridges and adhesion fundamentally and adversely affect the dispensing function of the device. In addition, even if the device still dispenses accurately, problems still exist. One such problem is bulk material adhering to the wall of the feeding funnel. It is possible, at a later stage, for the aged, sticking or baked bulk material to break loose from the feeding funnel. This breaking off is totally unacceptable in view of the required quality of the bulk material, or in the case of food, for hygienic reasons. The wedge shape of the feeding funnel favors the occurrence of such defects.
DE 198 28 559 C1 illustrates a dispensing device of a similar type. Here the assembly includes a conical feeding tunnel and an adjoining filler pipe. A spiral-shaped, rotatingly drivable conveying unit is positioned in the filler pipe. An independently rotatingly drivable and axially displaceable closing element is arranged. The conveying unit extends upwardly into the feeding funnel. The conveying unit carries a bar-shaped stirring mechanism at its upper end in the feeding funnel. The closing element can be withdrawn into the filler pipe towards the conveying spiral ending at a higher level to open an annual exit gap. This can result in a compaction of the flow of filled-in bulk material and to dispensing interference.
It is an object of the present invention to provide a method and device that dispenses problematic bulk material. Accordingly, sticky bulk material with a tendency to form bridges can be dispensed in constant quantities and in a constant material quality. A first solution provides a method where the bulk material, while being conveyed by the conveying unit in the filler pipe, is simultaneously mechanically agitated by an agitating means in the feeding funnel. This solution provides a device including a feeding funnel with a conical shape and agitating elements close to the wall of the feeding funnel. The agitating elements are rotatably drivable around the funnel axis. In a second solution, the bulk material, while being conveyed by the conveying unit in the filler pipe, is simultaneously mechanically conveyed by conveying means in the feeding funnel feeding bulk material towards the filler pipe. This solution provides a device including a conical shape feeding funnel. Conveying elements are rotatably drivable around the funnel axis in the feeding funnel.
These two solutions can be used on their own or in combination with one another. According to the first solution, the bulk material is agitated in the feeding funnel. The agitating elements are close to the funnel wall preventing any bulk material from adhering to the wall. This ensures a constant flow of material to the filler pipe. The agitating elements are in the form of leaves extending parallel to the wall of the feeding funnel. The leaves are preferably arranged to extend axially non-displaceable relative to the funnel axis. The leaves are at a constant distance from the funnel wall. The constant distance of the leaves from the wall of the feeding funnel ensures that the agitating process is continuously effective. Agitation in the feeding funnel takes place at a lower rotation frequency than the driving of the conveying unit for the purpose of conveying the bulk material in the filler pipe. The agitating elements in the feeding funnel and the conveying unit in the filler pipe can be driven, via suitable transmission ratios, by a common drive unit. Also it is possible to provide separate drive units. Thus, continuous agitation in the feeding funnel is possible even in cases where the rotatingly drivable conveying unit is not driven and when the closing element is in the closed position.
According to a second solution, inside the feeding funnel, especially in a central region, the bulk material is additionally conveyed towards the filler pipe. If there is only a risk of forming bridges of powdery materials and if the stickiness of the material is less of a concern, the second solution ensures a reliable flow of material from the feeding funnel into the filler pipe. Accordingly, the conveying means in the filling funnel is driven at the same rotation frequency as the conveying unit in the filler pipe conveying the bulk material. In this connection, the conveying elements in the feeding funnel are arranged at a constant axial distance from the conveying unit in the filler pipe. Thus the lifting and lowering of the conveying unit cannot result in internal compaction processes. It is particularly advantageous to use the same drive unit. The drive unit can also act on a single common drive shaft. The drive shaft is firmly connected to both the conveying unit in the filler pipe, with an attached closing element, and to the additional conveying elements in the feeding funnel. The shaft is axially adjustable together with the driving motor or relative to the driving motor.
According to a second variant, the conveying elements in the feeding funnel are axially firmly positioned in the feeding funnel, especially in the upper funnel region. Thus, the distance from the axially displaceable conveying unit changes when opening and closing the closing element. This embodiment enables a common drive unit, but it has to drive two shafts which are arranged one inside the other. The shafts are axially displaceable relative to one another. The shafts are provided for the conveying elements in the feeding funnel and for the conveying unit in the filler pipe. The additional conveying elements may have the shape of a worm portion, of individual blades or of a spiral portion. The conveying elements comprise a gradient relative to the axis of the feeding funnel.
On the upper face of the closing element, which is rotatingly drivable together with the conveying unit, it is possible to arrange blades with or without a gradient relative to the longitudinal axis. The blades improve the dispensing flow. The rotational and axial movement of the conveying unit and closing element can, as is already known, be controlled independently of one another or depend on one another in accordance with certain functions. The closing cone at the lower end of the conveying unit is preferably removably attached. However, in the fully assembled condition, the two parts form a structural unit. In this way, pockets of dirt and dead spaces in the material flow can already largely be avoided by design measures. The conveying unit is preferably an endless worm on a central shaft. In a preferred embodiment, the closing cone has the same cross-section as the shaft where it directly joins the shaft. In its lowest region with the greatest diameter, the closing cone includes a sealing portion. When the closing cone is in the lifted position, the sealing portion sealingly rests against the lower end of the filler pipe.
Additional objects and advantages of the present invention will become apparent from the detailed description of the preferred embodiment, and the appended claims and accompanying drawings, or may be learned by practice of the invention.